Improvement of Pulsed Holographic Recording Characteristics of Polyvinyl Alcohol/Acrylamide Green-Sensitive Photopolymer

2014 ◽  
Vol 1035 ◽  
pp. 492-496
Author(s):  
Gang Chen ◽  
Jian Hua Zhu ◽  
Zhen Xiong Luo ◽  
Yu Zhao ◽  
Ze Ren Li
Keyword(s):  
Energy Density ◽  
Polyvinyl Alcohol ◽  
Diffraction Efficiency ◽  
Delay Time ◽  
High Speed ◽  
Transient Processes ◽  
Holographic Recording ◽  
Application Prospects

Coherent pre-illumination technique is proposed to improve the pulsed holographic recording characteristics of polyvinyl alcohol (PVA) /acrylamide green-sensitive photopolymer. By optimizing the pre-illumination parameters such as pre-illumination energy density and pre-illumination delay time, the photosensitivity and diffraction efficiency of photopolymer under pulsed holographic recording are improved effectively. For the coherent pre-illumination energy density of 2mJ/cm2, total pre-illumination energy of 50mJ/cm2, the diffraction efficiency of 85% can be obtained with holographic exposure of 35mJ/cm2. For the coherent pre-illumination delay time of 20seconds, the diffraction efficiency of 60% is obtained with holographic exposure of 17.5mJ/cm2. The photosensitivity is successfully improved about 8 times compared with other reported results, it has good application prospects in the measurements of high-speed transient processes.

Research on Prediction of High-Speed Rail Trains Delay Time

CICTP 2020 ◽  
2020 ◽  
Author(s):  
Jing Shi ◽  
Qiyuan Peng ◽  
Ling Liu
Keyword(s):  
Delay Time ◽  
High Speed ◽  
High Speed Rail

scholarly journals Neuro-Inspired Computing with Spin-VCSELs

2021 ◽  
Vol 11 (9) ◽  
pp. 4232
Author(s):  
Krishan Harkhoe ◽  
Guy Verschaffelt ◽  
Guy Van der Sande
Keyword(s):  
Processing Speed ◽  
Delay Time ◽  
High Speed ◽  
State Of The Art ◽  
Polarization Modulation ◽  
Time Interval ◽  
Computing Technique ◽  
High Modulation ◽  
Short Time ◽  
Modulation Speed

Delay-based reservoir computing (RC), a neuromorphic computing technique, has gathered lots of interest, as it promises compact and high-speed RC implementations. To further boost the computing speeds, we introduce and study an RC setup based on spin-VCSELs, thereby exploiting the high polarization modulation speed inherent to these lasers. Based on numerical simulations, we benchmarked this setup against state-of-the-art delay-based RC systems and its parameter space was analyzed for optimal performance. The high modulation speed enabled us to have more virtual nodes in a shorter time interval. However, we found that at these short time scales, the delay time and feedback rate heavily influence the nonlinear dynamics. Therefore, and contrary to other laser-based RC systems, the delay time has to be optimized in order to obtain good RC performances. We achieved state-of-the-art performances on a benchmark timeseries prediction task. This spin-VCSEL-based RC system shows a ten-fold improvement in processing speed, which can further be enhanced in a straightforward way by increasing the birefringence of the VCSEL chip.

scholarly journals Diffraction Efficiency Characteristics for MEMS-Based Phase-Only Spatial Light Modulator with Nonlinear Phase Distribution

Photonics ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 62
Author(s):  
Remington S. Ketchum ◽  
Pierre-Alexandre Blanche
Keyword(s):  
Diffraction Efficiency ◽  
High Speed ◽  
Phase Distribution ◽  
Complex Structure ◽  
Spatial Light Modulators ◽  
Light Modulator ◽  
Micro Electro Mechanical Systems ◽  
Light Modulators ◽  
Nonlinear Phase ◽  
Liquid Crystal On Silicon

Micro-electro mechanical systems (MEMS)-based phase-only spatial light modulators (PLMs) have the potential to overcome the limited speed of liquid crystal on silicon (LCoS) spatial light modulators (SLMs) and operate at speeds faster than 10 kHz. This expands the practicality of PLMs to several applications, including communications, sensing, and high-speed displays. The complex structure and fabrication requirements for large, 2D MEMS arrays with vertical actuation have kept MEMS-based PLMs out of the market in favor of LCoS SLMs. Recently, Texas Instruments has adapted its existing DMD technology for fabricating MEMS-based PLMs. Here, we characterize the diffraction efficiency for one of these PLMs and examine the effect of a nonlinear distribution of addressable phase states across a range of wavelengths and illumination angles.

scholarly journals Holographic Recording Performance of Acrylate-Based Photopolymer under Different Preparation Conditions for Waveguide Display

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 936
Author(s):  
Zhongwen Shen ◽  
Yishi Weng ◽  
Yuning Zhang ◽  
Chuang Wang ◽  
Ao Liu ◽  
...  
Keyword(s):  
Augmented Reality ◽  
Diffraction Efficiency ◽  
Green Light ◽  
Holographic Recording ◽  
Holographic Gratings ◽  
Preparation Conditions

This work proposes a green light-sensitive acrylate-based photopolymer. The effects of the preparation conditions for the waveguide applied volume holographic gratings (VHGs) were experimentally investigated. The optimum preparation conditions for holographic recording were revealed. After optimization, the peak of VHG diffraction efficiency reached 99%, the diffractive wavelength bandwidth increased from 13 nm to 22 nm, and the corresponding RIM was 0.06. To prove the wide application prospect of the acrylate-based photopolymer in head-mounted augmented reality (AR) displays, green monochromatic volume holographic waveguides were fabricated. The display results showed that the prototype was able to achieve a 28° diagonal FOV and possessed a system luminance of 300 cd/m2.

Highly reversible aluminium-sulfur batteries through effective sulfur confinement with hierarchical porous carbon

2021 ◽  
Author(s):  
Dian Zhang ◽  
Xu Zhang ◽  
Boya Wang ◽  
Shiman He ◽  
Shiqi Liu ◽  
...  
Keyword(s):  
Energy Density ◽  
Porous Carbon ◽  
Low Cost ◽  
Hierarchical Porous Carbon ◽  
Hierarchical Porous ◽  
Application Prospects

Aluminium-sulfur (Al-S) batteries possess high research merits and application prospects owing to their high theoretical energy density, high safety and low cost. However, the deficiency of outstanding cathodes severely limits...

Effect of the Structure and Content of Carbazolyl-Containing Co-oligomers on the Diffraction Efficiency of Holographic Recording Media

2015 ◽  
Vol 51 (1) ◽  
pp. 67-71 ◽  
Author(s):  
Yu. P. Getmanchuk ◽  
N. A. Davidenko ◽  
I. I. Davidenko ◽  
E. V. Mokrinskaya ◽  
V. A. Pavlov ◽  
...  
Keyword(s):  
Diffraction Efficiency ◽  
Holographic Recording ◽  
Recording Media ◽  
Holographic Recording Media

Laser-Triggered Surface Flashover Characteristics of Al2O3 in Pulsed Voltage

2011 ◽  
Vol 354-355 ◽  
pp. 1224-1227
Author(s):  
Ru Zheng Pan ◽  
You Hua Wang ◽  
Min Tang Li ◽  
Ling Ling Pang ◽  
Jue Wang ◽  
...  
Keyword(s):  
Energy Density ◽  
Nd:Yag Laser ◽  
Delay Time ◽  
Laser Energy ◽  
Test System ◽  
Vacuum Condition ◽  
Surface Flashover ◽  
532 Nm ◽  
Time Decrease ◽  
Pulsed Voltage

Based on the platform of laser-triggered surface flashover in pulsed voltage, experiment of laser-triggered surface flashover is carried out in air and vacuum condition with pulsed voltage. A single/double harmonic, with wavelength of 1064/532 nm, Q-switched Nd:YAG laser is applied to trigger the surface flashover. The test system consists of flat electrodes and columned insulator. The material of electrode is copper and the material of insulator is Al2O3. Laser pulse’s wavelengths are 532nm and 1064nm, and laser is focused with rectangle. The results of experiment show that flashover delay time and jitter time decrease with increase of pulsed voltage or laser energy density, the delay time of 1064nm laser trigger is larger than that of 532nm laser trigger, and the delay time and jitter time in vacuum condition are less than the delay time and jitter time in air condition.

Investigation of an Experimental Laser Sensor-Guided Spray Control System for Greenhouse Variable-Rate Applications

2019 ◽  
Vol 62 (4) ◽  
pp. 899-911
Author(s):  
Tingting Yan ◽  
Heping Zhu ◽  
Li Sun ◽  
Xiaochan Wang ◽  
Peter Ling
Keyword(s):  
Control System ◽  
Delay Time ◽  
High Speed ◽  
Laser Scanning ◽  
Plant Production ◽  
Laser Sensor ◽  
Variable Rate ◽  
Spray Volume ◽  
Spray Control ◽  
Variable Rate Spraying

Abstract. Precision variable-rate spraying technology is needed for controlled-environment plant production in greenhouses. An experimental spray system for greenhouse applications was developed for real-time control of individual nozzle outputs. The system mainly consisted of a high-speed laser scanning sensor, 12 individual variable-rate nozzles, an embedded computer, a spray control unit, and a 3.6 m long mobile spray boom. Each nozzle was coupled with a pulse-width modulated solenoid valve to discharge sprays at variable rates based on target presence and plant canopy structure. Laboratory tests were conducted to evaluate the accuracy of the spray control system in respect to spray delay time, nozzle activation, and spray volume using four target objects of different regular geometrical shapes and surface textures and two artificial plants of different canopy structures. Other experimental variables included three detection heights from 0.5 to 1.0 m and five sensor travel speeds from 1.6 to 4.8 km h-1. A high-speed video camera was used to determine the delay time and nozzle activation in discharging sprays on target objects after the laser sensor had detected the objects. The detection height and travel speed were found to have slight influence on the timing of nozzle activation. The nozzles started spraying in a range between 33 and 83 mm before reaching the target objects and stopped spraying between 13 and 84 mm after passing the objects, ensuring that the objects were fully covered by the spray. Spray volume corresponded to the object sizes well, and the spray control system performed with higher accuracy at lower travel speeds. Differences between the calculated spray volume based on the sensor detection and the actual spray volume ranged from 1.9 to 2.7 mL per object among all tested objects. The variable-rate control system reduced spray volume by 29.3% to 51.4% for all the objects compared with conventional constant-rate spraying. At the same time, the nozzles could be activated precisely by the object presence. Consequently, this experimental laser-guided system was implemented on a boom system in a commercial greenhouse for future investigations of its accuracy in variable-rate spraying to save pesticides, water, and nutrients. Keywords: Automation, Intelligent sprayer, Pesticide, Precision spray technology, Boom spray equipment.

scholarly journals Study on the Ignition Process and Characteristics of the Nitrate Ester Plasticized Polyether Propellant

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Xiaoting Yan ◽  
Zhixun Xia ◽  
Liya Huang ◽  
Likun Ma ◽  
Xudong Na ◽  
...  
Keyword(s):  
Grain Size ◽  
Energy Density ◽  
Ignition Delay ◽  
Delay Time ◽  
Ignition Temperature ◽  
Ignition Delay Time ◽  
Ignition Process ◽  
Ignition Energy ◽  
Nitrate Ester ◽  
Nepe Propellant

In this study, a CO2 laser ignition experimental system was built to study the ignition process and characteristics of the Nitrate Ester Plasticized Polyether (NEPE) propellant. The effect of the energy density, ingredients, and the grain size distribution of the propellant on the ignition process was investigated using a CO2 laser igniter, a high-speed camera, and a tungsten-rhenium thermocouple. Four types of NEPE propellants were tested under different laser heat fluxes, and the ignition delay time, the ignition temperature, and the ignition energy were obtained. Experimental results show that the ignition process of the NEPE propellant can be divided into three stages, namely the first-gasification stage, the first-flame stage, and the ignition delay stage. When the energy density is lower than the ignition energy threshold, the ignition process cannot be achieved even under continuous energy loading. The increase of the energy density can lead to the decrease of the ignition delay time but has little effect on the ignition temperature. The ingredients and grain size distribution have great effects on both the ignition delay time and the ignition temperature. The grain size effect of aluminum is the largest compared with that of Ammonium Perchlorate (AP) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), while the grain size effect of AP is larger than that of HMX.

Sign in / Sign up

Export Citation Format

Share Document